RANSOM_CRYPWALL.YUYAIQ

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

However, as of this writing, the said sites are inaccessible. It deletes itself after execution. It is capable of encrypting files in the affected system.

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops and executes the following files:

• %Desktop%\HELP_YOUR_FILES.TXT
• %Desktop%\HELP_YOUR_FILES.HTML
• %Desktop%\HELP_YOUR_FILES.PNG

(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following copies of itself into the affected system:

• %Application Data%\{random characters}\{random characters}.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random characters} = "%Application Data%\{random characters}\{random characters}.exe"

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableSR = "1"

(Note: The default value data of the said registry entry is "0".)

Dropping Routine

This Trojan drops the following files:

• HELP_YOUR_FILES.PNG - drops to all folders where files are encrypted
• %User Startup%\HELP_YOUR_FILES.TXT
• %User Startup%\HELP_YOUR_FILES.HTML
• %User Startup%\HELP_YOUR_FILES.PNG

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Other Details

This Trojan connects to the following possibly malicious URL:

• {BLOCKED}.com/LAUe18.php?{random letter}={random value}
• {BLOCKED}g.de/_rQbc5.php?{random letter}={random value}
• {BLOCKED}8londonescorts.com/3xd2TW.php?{random letter}={random value}
• {BLOCKED}6beta.com/YTKUmk.php?{random letter}={random value}
• {BLOCKED}lutions.com.br/DoPk50.php?{random letter}={random value}
• {BLOCKED}y60.tk/8fyYij.php?{random letter}={random value}
• {BLOCKED}volosuk.com/RWHtPX.php?{random letter}={random value}
• {BLOCKED}ndnoble.com/eFSR79.php?{random letter}={random value}
• {BLOCKED}laboratuvar.com/_E9Oth.php?{random letter}={random value}
• {BLOCKED}point.ua/Q0Gtjw.php?{random letter}={random value}
• {BLOCKED}yfive.com/cxhlow.php?{random letter}={random value}
• {BLOCKED}.udraw.net/tZ6dGp.php?{random letter}={random value}
• {BLOCKED}oexperto.pe/93KW78.php?{random letter}={random value}
• {BLOCKED}hnologies.asia/otsPle.php?{random letter}={random value}
• {BLOCKED}tednetworktools.com/Y8L9Au.php?{random letter}={random value}
• {BLOCKED}o.pl/ZmarLT.php?{random letter}={random value}
• {BLOCKED}a-physio.com/GToz01.php?{random letter}={random value}
• {BLOCKED}ble-bikes.com/PJWwyK.php?{random letter}={random value}
• {BLOCKED}.kz/B68uyb.php?{random letter}={random value}
• {BLOCKED}13.tk/jie6Al.php?{random letter}={random value}
• {BLOCKED}dwater.com/B4YjMo.php?{random letter}={random value}
• {BLOCKED}acker.eu/aAm73E.php?{random letter}={random value}
• {BLOCKED}scottage.at/GIDtTa.php?{random letter}={random value}
• {BLOCKED}edeerhill.co.uk/65Dprd.php?{random letter}={random value}
• {BLOCKED}ashnmoney.com/A9rWa2.php?{random letter}={random value}
• {BLOCKED}esxvideos.com/ioaTQC.php?{random letter}={random value}
• {BLOCKED}arga.co/K_5JtY.php?{random letter}={random value}
• {BLOCKED}maedels-luisenfelde.de/af1xLZ.php?{random letter}={random value}
• {BLOCKED}ityconsignment.com/s4CLVv.php?{random letter}={random value}
• {BLOCKED}t.mysite.am/HLUsrb.php?{random letter}={random value}
• {BLOCKED}lienka.sk/vF9T2e.php?{random letter}={random value}
• {BLOCKED}jitsingh.in/3FD9Wc.php?{random letter}={random value}
• {BLOCKED}pl/EnUC5z.php?{random letter}={random value}
• {BLOCKED}diodnye-svetilniki.com/Lvz9rX.php?{random letter}={random value}
• {BLOCKED}eklypizza.com/N_X8BJ.php?{random letter}={random value}
• {BLOCKED}igloan.com/PFN3Dy.php?{random letter}={random value}
• {BLOCKED}help.com/Dl17Ze.php?{random letter}={random value}
• {BLOCKED}site.com/M6w4gu.php?{random letter}={random value}

However, as of this writing, the said sites are inaccessible.

It deletes itself after execution.

It is capable of encrypting files in the affected system.